<?xml version="1.0" encoding="UTF-8"?>
<Dictionary xmlns="http://www.opengis.net/gml" xmlns:gml="http://www.opengis.net/gml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/gml ../../gml/3.1.1/base/dictionary.xsd" gml:id="VerticalDatumType">
	<!-- Primary editor: Arliss Whiteside. Last updated 2005-09-12-->
	<name>Vertical Datum Type standard values</name>
	<!-- ===================================================== -->
	<dictionaryEntry>
		<Definition gml:id="geoidal">
			<description>The zero value of the associated vertical coordinate system axis is defined to approximate a constant potential surface, usually the geoid. Such a reference surface is usually determined by a national or scientific authority, and is then a well-known, named datum. </description>
			<name codeSpace="urn:ogc:def:pixelInCell:OGC:1.0:">geoidal</name>
		</Definition>
	</dictionaryEntry>
	<dictionaryEntry>
		<!-- ===================================================== -->
		<Definition gml:id="depth">
			<description>The zero point of the vertical axis is defined by a surface that has meaning for the purpose which the associated vertical measurements are used for. For hydrographic charts, this is often a predicted nominal sea surface (i.e., without waves or other wind and current effects) that occurs at low tide. </description>
			<name codeSpace="urn:ogc:def:pixelInCell:OGC:1.0:">depth</name>
		</Definition>
	</dictionaryEntry>
	<!-- ===================================================== -->
	<dictionaryEntry>
		<Definition gml:id="barometric">
			<description>Atmospheric pressure is the basis for the definition of the origin of the associated vertical coordinate system axis. </description>
			<name codeSpace="urn:ogc:def:pixelInCell:OGC:1.0:">barometric</name>
		</Definition>
	</dictionaryEntry>
	<dictionaryEntry>
		<!-- ===================================================== -->
		<Definition gml:id="otherSurface">
			<description>In some cases, e.g. oil exploration and production, a geological feature, such as the top or bottom of a geologically identifiable and meaningful subsurface layer, is used as a vertical datum. Other variations to the above three vertical datum types may exist and are all included in this type. </description>
			<name codeSpace="urn:ogc:def:pixelInCell:OGC:1.0:">otherSurface</name>
		</Definition>
	</dictionaryEntry>
</Dictionary>
